Hollow conductor



Dec. 26, 1939. l W LOWE 2,184,391

HOLLOW CONDUCTOR Filed Jan. '7, 1937 'ff/ Fw 6 9 NVENTOR ATTORNEYS.

Patented Dec. 26, 1939 HOLLOW CONDUCTOR William Lowe, Ansonia, Conn., assignor to Anaconda Wire and Cable Company, New York, N. Y., a corporation of Delaware Application January 7, 1937, Serial No. 119,435

6 Claims.

This invention relates to new and useful yimprovements in hollow electrical conductors, especially conductors for power transmission lines for high voltage alternating currents, and has particular relation to such hollow conductors as are made up of a plurality of strands or segmental wires of suitable metal, such for example as copper and copper alloys, or other alloys or metal having the desired strength and electrical conductivity.

An object of the invention is to provide a` hollow conductor of the type indicated which is of improved construction, has better flexibility, has smooth round inside and outside surfaces,

and which for same thickness of cable wall has thinner strands.

Another object is to provide a hollow conductor of such construction that tension tends to close or pull the strands or segmental wires in instead of opening out or spreading so it will not squirrel-cage or open radially, and which will have long useful life.

A further object is to provide a hollow cable construction in which the full strength of the metal used in the cable is utilized to resist stresses and deformation of all kinds to a greater extent than previous conftructions; that is, to produce a construction in which. while permitting longitudinal movement between the segmental wires, the assembly approaches the characteristics of a solid tube in resisting section deformation.

Other objects and advantages will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawing where in a satisfactory embodiment of the invention is shown. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention and the scope of the appended claims.

In the drawing:

Fig. 1 is a view illutrating the method of making the improved conductor, the view being taken at the die employed;

Fig. 2 is a view on a smaller scale-and illustrating the method more completely;

Fig. 3 is an enlarged detail sectional view taken substantially along the line 3--3 of Fig. l;

Fig. 4 is an enlarged detail sectional view taken as along the line 4 4 of Fig. 1;

Fig. 5 is an enlarged end elevational view of one of the strands or segmental wires employed;

Fig. 6 is a side view of a portion of the strand or wire of Fig. 5.

Referring in detail to the drawing, the improved cable generally designated I0 is made up of inner and outer layers II and I2, each such o layer consisting of a plurality of similar strands or segmental wires I3, although due to the difference in diameter the wires or segments in the outer layer are slightly wider than the wiresor segments in the inner layer. These segmental wires I3 may be drawn, and in their original 5 state, before being fabricated into the conductor, may be cross-sectionally flat as shown in Figs. 3 and 5, or curved similar to their shape in the completed cable if preferred. In one longitudinal edge, each wire is provided with a suitably 10 shaped groove I4 but which is preferably V-shaped, and on its opposite longitudinal edge with a similarly shaped projection or edge I5. Although the substantial V-shape shown is preferred I am not limited to this shape, as the rel5 sult can be accomplifhed with other in effect concave or trough shaped and convex-edges, and which may be curved or circular or any other suitable shape in cross section. In other words,

one longitudinal edge is grooved and the other 20 edge is shaped to seat in the groove in the edge of the next adjacent segment. so that, as will be shown later, adjacent segmental wires are held against separation or relative lateral movementin a direction radially of the cable. The substantially V-shape as suggested in Fig. 5 is preferred as it gives a good firm abutment and holding effect between adjacent wires and good strength and stiffness to the edges on the opposite sides of the groove. Additionally in one side 30 each strand is provided with a relatively wide channel I6, the respective edges of which are undercut as at I 1 and I8 whereby the channel is wider at the bottom or inner surface and the edges I1 and I8 overhang somewhat. This 35 groove or channel I6 thus provides two spaced longitudinal ribs or ridges 8 and 9 on one side of the strand.

The method of fabricating the conductor I0 will be but briefly referred to herein as -such 40 method `forms the subject matter-of a separate application which issued as Patent Number 2,136,388 November 15, 1938. As suggested in Fig. 2 the strands or segmental wires I3 are wound on stationary reels I9 from which the 45 wires are fed through guides 20 and 20a to a die in the form of a ring 2|. This die is supported in any desired manner as on an upright 22 (Fig. l). The guide openings in the guide 20a are offset laterally or peripherally from those in 50 the guide 20 so that as the wires pars through these guides they are first bent or curved in one direction as indicated at I3a and then bent or curved in another direction as indicated at I3b so that the wires are given a preliminary bend 55 cr twist, similar to their nal spiral shape in the cable, before they pass through the die 2l.

In passing through the die 2|, the wires pass about a tapered plug 23 held in the desired relation to the tapered opening 2id in the die as by 60 screw 24 passing through a suitable support 25. Screw 24 has a smooth end portion 26 of reduced diameter located in a socket 21 in the plug whereby on adjustment of the screw through the support 25 the plug is properly located in the die 2 I. l

The plug 23 is a tapered plug running into a tapered die. This plug is a guide that carries the strands or grooved wires into the die 2|, and the plug guides the wires in such manner that the edges of the wires naturally come together, the V-shaped (or other shaped) projectiony or edge I5 of one wire entering the V-shaped (or other shaped) groove I4 in the edge of an adjacent wire, and the inner layer forms a supporting arch for the outer wires. Also, the wires are so guided that the ribs 8 and 9 of each layer are seated in the channels I6 of the other layer so that the two layers are held against lateral relative movement in a direction radially of the cable. The nested wires are drawn through the die due to the turning of adrum or capstan 28 on which the finished conductor is being wound. As the drum draws the wires through the die they are curved transversely if they are not previously curved and the complete conductor is given its round circular shape with continuous circular outer and inner surfaces, and the wires are given a further twist if necessary by the action of the drum which is bodily rotated about the axis of the cable, so that they extend spirally as shown in Fig. 1. This is desirable in order that the conductor shall have the desired exibility. As the wires pass through the die the outer wires or layer are supported and held to form by the inner layer. This is because as the inner wires are guided into the die by the plug these wires or segments I3 form an arch which is self supporting and thus forms 'a support for the outer layer which holds this outer layer to form.

In the completed conductor the adjacent wires or segments of the respective layers II and I2 are connected so they cannot separate in a direction radially of the conductor due to the entrance of the projection I5 at the edge of one Wire or segment into the V-shaped groove I4 at the adjacent edge of the next adjacent wire or segment. Obviously as long as the wires are maintained in this relation, the conductor can not open up or bird-cage.

In addition to one edge of each of the wires of a layer being in a groove in the adjacent edge of the adjacent wire of that layer, the wires of each layer are connected with those of the other layer in such manner ato keep the edges of the Wires of that other layer together and prevent their separating in a direction circumferentially of the cable, and also to prevent the layers' separating radially of the conductor. As the wires are about to enter the die 2| they are related to one another substantially as shown in Fig. 3 and are yet fiat, (unless they are previously curved) but as they pass into the die are nested and connected together.

In passing through the die they are forced into a transversely curved condition so that the conductor is given its circular shape and its smooth continuously curved inner and outer surfaces. In the finished conductor as shown in Fig. 4 the inner layer I2 forms a supporting arch for the layer ofv outer wires. Referring particularly tothe Wires A, B and C in Fig. 4, it is'noted that A and B being a pair of wires, their portions between their channels IB, are both received in the said channel of the wire C. Thus the projection I5 at one edge of Wire B is maintained in the groove I4 in the edge of Wire A and there is no possibility of the joint between wires A and B opening up.

The edges of the channels of the various wires being undercut at I1 and I8, when the adjacent portions of a pair of wires of. one layer are received in a channel of a wire of the next layer, the overlapping joints are secured as at 29. From this it will be seen that the wires of each layer span or bridge the joints between the wires of the other layer and in each instance secure together the two Wires forming such joint of the other layer. Thus each wire is secured in place by coacting means at each of its longitudinal edges and by coacting means 29 at each longitudinal edge of its channel I6. Also, the Wires of the two layers are secured together by the overhang I1 and I8 so that they cannot separate radially.

It is to be noted that both the inner and outer surfaces of the finished conductor are round and smooth. The adjacent wires may slide longitudinally on each other to permit the cable to flex. If desired the contacting surfaces may be lubricated by graphite or similar material to improve this action. This cable therefore although the Wires are all securely connected is flexible, has round smooth inner and outer surfaces, and it is ofv uniform wall thickness throughout. The flexibility is further improved because with this construction for the same thickness of cable wall thinner wires are used. The inner layer of wires as will be seen from Fig. 4 forms an arch support for the outer layer and holds it to form. Tension on the cable tends to pull the wires in instead of opening out or spreading. The fact the wires are on a spiral helps this. However as the outer layer of wires tends to pull in it is supported by the arch shaped inner layer which cannot yield inwardly and is self supported because of the arch effect. Therefore tension on the cable tends to pull and hold the wires together instead of separating them or opening out the cable. This together with the manner of securing the wires together resists or Withstands vibration much better and with less danger of the wires separating and the cable opening up. This has been a serious objection to cables previously on the market and it has been necessary to add auxiliary devices to these cables to prevent the strands separating or the cable opening up.

Although a self-supporting hollow conductor has been known, it has been found to be mechanically weak, particularly with respect to compressive strength. High compressive strength is necessary for clamping and splicing, and it isy also desirable to facilitate handling in construction. In addition to the above weakness the known conductors have mechanical weakness in withstanding radial and longitudinal stresses imposed in construction and in service. It will therefore be seen it is desirable that the full strength of the metal used in the cable be used to resist stresses and deformation oi all kinds. In other words` While permitting longitudinal movement between the segmental Wires, the assembly should approach the characteristics of a solid tube in resisting section deformation. The present construction has accomplished these results and overcome the previous objections to -a marked degree. The groove in one edge of each wire in which the edge of the adjacent Wire seats provides a secure abutment between the segments and retains them in the proper relative positions.

amasar A'3 Also, the manner of securing the wires of. one layer to those of another greatly assists in securing these results and advantages.

Another advantage of the present construction is that after assembly this cable can, within limits, be reduced in cross sectional area, that is, wall thickness and to some extent in overall diameter, by drawing in dies, as in a tubemrnill. This is accomplished without undue deformation of the individualsegmental wires, and appears to reduce the sectional area of all of them proportionately. This is believed to have distinct novelty in conductor manufacture and commercial applicaton in minimizing the number of separate dies and sizes of wire which must be used.`

It further has the feature that wall thickness of the hollow conductor can be reduced below thicknesses obtainable by any other manufacturing method.

It will also be seen from the above disclosure that the wires of both layers lie orare stranded in the same spiral direction. Therefore the joint between any two adjacent wires of either layer is always covered by a wire of the other layer, and the overlapped Wires of the two layers are effectively secured together throughout their entire lengths.

This construction of cable has the further advantage that one layer can be made of material having much higher strength and hardness than the other layer, which latter layer may be of a metal of high electrical conductivity. Thus, for example, the inner layer can be made of bronze or other high strengthmaterial while the outer layer is made of copper to obtain satisfactory electrical conductance. This also has the advantage where the cable is to be used for high voltage alternating currents in placing the metal of higher conductivity at the portion of the cross section of largest diameter. Conversely, if the cable is to be used in a location Where it might be subjected to severe abrasion, the outer layer could be composed of bronze or other suitable metal while the inner layer could be of copper to supply satisfactory conductive properties.

Having thus set forth the nature of my invention, what I claim is:

1. A hollow iiexible conductor comprising inner and outer layers of preformed segmental wires, the adjacent wires of the respective layers being formed at their engaging edges with cooperating means securing each of them against separation relative to the other in a direction radially of the conductor, said inner layer of wires forming a supporting arch for the layer of outer wires, cooperating means integral with the two layers of wires securing the layers against separation radially of the conductor, and adjacent wires beinglongitudinally slidable relative to each other to permit exing of the conductor.

2. A hollow exible conductor comprising inner and outer layers of preformed wires, the adjacent wires of the respective layers at their engaging edges having cooperating means to secure each of them against movement relative to the other in a direction radially of the conductor, each of the wires of each layer spanning a joint between a pair of adjacent wires of the other layer, the adjacent wires being longitudinally slidable relative to each other whereby a. fiexible conductor is provided, and cooperating means on the overlapped wires of the two layers to hold each adjacent pair of wires in abutting relation and retain the cooperating securing means together and also secure the two layers against separation in a direction radially of the conductor.

3. A hollow flexible conductor comprising inner and outer layers of preformed segmental wires each having a projection on one and a groove in its other longitudinal edge both extending throughout the length of the wire and so shaped that the edges of adjacent wires seat one in the other and are held against separation in a direction radially of the conductor at their adjacent edgesg said wires each having a single dovetail channel in one side, said wires of the inner layer being` in reversed relation with respect to those of the outer layer whereby the channeled sides of the wires face one another, said wires being so arranged that each joint between adjacent wires of one layer is spanned by a wire of the other layer, and said channels being of such width that the portions of a pair of adjacent wires between the channels of such pair are received in the channel of the wire spanning the joint between such pair and hold the wires of the two layers against .separation in a direction radially of the conductor, the adjacent wires being longitudinally slidable relative to each other.

4. A hollow conductor comprising inner and outer layers of preformed wires, the adjacent wires of the respective layers at their engaging edges having cooperating means securing each of them against separation relative to the other in a direction radially of the conductor, said inner layer of wires forming a supporting archfor the layer of outer wires, the wires of said layers all extending spirally around the conductor in the same direction and longitudinally slidable relative to each other whereby a flexible conductor is provided,'and cooperating means on the wires of the inner and outer layers securing the layers against separation in a direction radially of the conductor.

5. A hollow conductor comprisingy innerv and outer layers of preformed segmental wires, each wire having a groove along one edge to receive the opposite edge of an adjacent wire, each wire also having in one side a single longitudinal undercut channel providing longitudinal ribs on said side having overhanging edges for the channel, and the wires in each layer being reversed with respect to the wires of the other layer and assembled with each wire of each layer vspanning the joint between two adjacent Wires of the other layer and with the two adjacent ribs of adjacent wires in each layer seated in the side channel of a wire of the other layer to hold the layers against I separation in a direction radially of the conductor, and adjacent wires being longitudinally slidable relative to each other whereby a flexible conductor is provided.

6. A preformed segmental wire for a hollow conductor having a substantially V-shaped groove in one edge running throughout the length of the wire and similarly shaped on the other edge to seat in the corresponding groove of a similar wire for relative longitudinal sliding movement, said wire having in one side wallv a single longitudinal channel forming undercut ribs at the opposite sidesv thereof which form overhanging edges for the channel, and said channel being of a width to receive the adjacent ribs of two adjacent wires placed at one side of the first wire in reversed. relation to the rst wire and to hold them against separation.

WILLIAM LOWE. 

